Transfer Cable Help AND Jtag Help

Ok so i want to mod my split screen for mw2 for aimbot and Unlimited Ammo and Rapid Fire but i dont know what to use, wether i download it from Modio or i get it from myself, it never works why? and i wanna know how to install a JTAG for my Regular XBOX.

Well for Split Screen modding
You need to clear your systems Catch (Removes patches) By going to system setting memory and pressing (Y) im not sure if this is 100% correct im doing it by memory :P
Download a Gamesave from modio
USE YOUR profile info (Console id and stuff)
Rehash and resign